Impact of Distributed Generation on relay protection and its improved Measures

By interconnecting the power system, distributed generation (DG) can not only improve the system reliability, but also enhance the robustness against some emergencies such as snow storm etc. However, the increasing penetration of DG in power systems will deeply affect the distribution network topology, the amplitude and distribution of short-circuit current in the existing distribution network, and consequently the operation and control of the distribution network. To satisfy the requirements and resolve the existing problems of the relay protection of the distribution systems under high DG penetration level, a new protection scheme is introduced in this paper. The new protection scheme is based on longitudinal comparison principle. With the support of advanced communication infrastructure, the new scheme is based on substation-oriented master-slave structure, with the capability of protecting the whole distribution substation and all of its outgoing feeders under high DG penetration level.